Hello!
First off, I hope I'm not completely wrong in this part of the Forum but I've failed to find any better place for my question.

I have finally reached level 50 and want to buy the DLC soon. I have read about people having trouble because they bought it from the wrong place.

I own and play the game through Steam, I believe that's the only way I played (I had a long break) so I guess that's how I created my account too. (Any way to check and be sure how I created my account?)
But on the DLC page on Steam I've seen quite a few reviews saying not to buy the DLC on Steam.
At the same time I get warned not to buy the non-Steam version if I play on Steam.

I'm confused and don't want to spend my money on a product that's going to be incompatible with my game.
Thanks for your help!